function _extends() { _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; }; return _extends.apply(this, arguments); }

function _typeof(obj) { if (typeof Symbol === "function" && typeof Symbol.iterator === "symbol") { _typeof = function _typeof(obj) { return typeof obj; }; } else { _typeof = function _typeof(obj) { return obj && typeof Symbol === "function" && obj.constructor === Symbol && obj !== Symbol.prototype ? "symbol" : typeof obj; }; } return _typeof(obj); }

(function (global, factory) {
	(typeof exports === "undefined" ? "undefined" : _typeof(exports)) === 'object' && typeof module !== 'undefined' ? module.exports = factory() : typeof define === 'function' && define.amd ? define(factory) : global.LazyLoad = factory();
})(this, function () {
	'use strict';

	var runningOnBrowser = typeof window !== "undefined";
	var isBot = runningOnBrowser && !("onscroll" in window) || typeof navigator !== "undefined" && /(gle|ing|ro)bot|crawl|spider/i.test(navigator.userAgent);
	var supportsIntersectionObserver = runningOnBrowser && "IntersectionObserver" in window;
	var supportsClassList = runningOnBrowser && "classList" in document.createElement("p");
	var defaultSettings = {
		elements_selector: "img",
		container: isBot || runningOnBrowser ? document : null,
		threshold: 300,
		thresholds: null,
		data_src: "src",
		data_srcset: "srcset",
		data_sizes: "sizes",
		data_bg: "bg",
		class_loading: "loading",
		class_loaded: "loaded",
		class_error: "error",
		load_delay: 0,
		auto_unobserve: true,
		callback_enter: null,
		callback_exit: null,
		callback_reveal: null,
		callback_loaded: null,
		callback_error: null,
		callback_finish: null,
		use_native: false
	};

	var getInstanceSettings = function getInstanceSettings(customSettings) {
		return _extends({}, defaultSettings, customSettings);
	};
	/* Creates instance and notifies it through the window element */


	var createInstance = function createInstance(classObj, options) {
		var event;
		var eventString = "LazyLoad::Initialized";
		var instance = new classObj(options);

		try {
			// Works in modern browsers
			event = new CustomEvent(eventString, {
				detail: {
					instance: instance
				}
			});
		} catch (err) {
			// Works in Internet Explorer (all versions)
			event = document.createEvent("CustomEvent");
			event.initCustomEvent(eventString, false, false, {
				instance: instance
			});
		}

		window.dispatchEvent(event);
	};
	/* Auto initialization of one or more instances of lazyload, depending on the
		options passed in (plain object or an array) */


	function autoInitialize(classObj, options) {
		if (!options) {
			return;
		}

		if (!options.length) {
			// Plain object
			createInstance(classObj, options);
		} else {
			// Array of objects
			for (var i = 0, optionsItem; optionsItem = options[i]; i += 1) {
				createInstance(classObj, optionsItem);
			}
		}
	}

	var dataPrefix = "data-";
	var processedDataName = "was-processed";
	var timeoutDataName = "ll-timeout";
	var trueString = "true";

	var getData = function getData(element, attribute) {
		return element.getAttribute(dataPrefix + attribute);
	};

	var setData = function setData(element, attribute, value) {
		var attrName = dataPrefix + attribute;

		if (value === null) {
			element.removeAttribute(attrName);
			return;
		}

		element.setAttribute(attrName, value);
	};

	var setWasProcessedData = function setWasProcessedData(element) {
		return setData(element, processedDataName, trueString);
	};

	var getWasProcessedData = function getWasProcessedData(element) {
		return getData(element, processedDataName) === trueString;
	};

	var setTimeoutData = function setTimeoutData(element, value) {
		return setData(element, timeoutDataName, value);
	};

	var getTimeoutData = function getTimeoutData(element) {
		return getData(element, timeoutDataName);
	};

	var purgeProcessedElements = function purgeProcessedElements(elements) {
		return elements.filter(function (element) {
			return !getWasProcessedData(element);
		});
	};

	var purgeOneElement = function purgeOneElement(elements, elementToPurge) {
		return elements.filter(function (element) {
			return element !== elementToPurge;
		});
	};

	var callbackIfSet = function callbackIfSet(callback, argument) {
		if (callback) {
			callback(argument);
		}
	};

	var updateLoadingCount = function updateLoadingCount(instance, plusMinus) {
		instance._loadingCount += plusMinus;

		if (instance._elements.length === 0 && instance._loadingCount === 0) {
			callbackIfSet(instance._settings.callback_finish);
		}
	};

	var getSourceTags = function getSourceTags(parentTag) {
		var sourceTags = [];

		for (var i = 0, childTag; childTag = parentTag.children[i]; i += 1) {
			if (childTag.tagName === "SOURCE") {
				sourceTags.push(childTag);
			}
		}

		return sourceTags;
	};

	var setAttributeIfValue = function setAttributeIfValue(element, attrName, value) {
		if (!value) {
			return;
		}

		element.setAttribute(attrName, value);
	};

	var setImageAttributes = function setImageAttributes(element, settings) {
		setAttributeIfValue(element, "sizes", getData(element, settings.data_sizes));
		setAttributeIfValue(element, "srcset", getData(element, settings.data_srcset));
		setAttributeIfValue(element, "src", getData(element, settings.data_src));
	};

	var setSourcesImg = function setSourcesImg(element, settings) {
		var parent = element.parentNode;

		if (parent && parent.tagName === "PICTURE") {
			var sourceTags = getSourceTags(parent);
			sourceTags.forEach(function (sourceTag) {
				setImageAttributes(sourceTag, settings);
			});
		}

		setImageAttributes(element, settings);
	};

	var setSourcesIframe = function setSourcesIframe(element, settings) {
		setAttributeIfValue(element, "src", getData(element, settings.data_src));
	};

	var setSourcesVideo = function setSourcesVideo(element, settings) {
		var sourceTags = getSourceTags(element);
		sourceTags.forEach(function (sourceTag) {
			setAttributeIfValue(sourceTag, "src", getData(sourceTag, settings.data_src));
		});
		setAttributeIfValue(element, "src", getData(element, settings.data_src));
		element.load();
	};

	var setSourcesBgImage = function setSourcesBgImage(element, settings) {
		var srcDataValue = getData(element, settings.data_src);
		var bgDataValue = getData(element, settings.data_bg);

		if (srcDataValue) {
			element.style.backgroundImage = "url(\"".concat(srcDataValue, "\")");
		}

		if (bgDataValue) {
			element.style.backgroundImage = bgDataValue;
		}
	};

	var setSourcesFunctions = {
		IMG: setSourcesImg,
		IFRAME: setSourcesIframe,
		VIDEO: setSourcesVideo
	};

	var setSources = function setSources(element, instance) {
		var settings = instance._settings;
		var tagName = element.tagName;
		var setSourcesFunction = setSourcesFunctions[tagName];

		if (setSourcesFunction) {
			setSourcesFunction(element, settings);
			updateLoadingCount(instance, 1);
			instance._elements = purgeOneElement(instance._elements, element);
			return;
		}

		setSourcesBgImage(element, settings);
	};

	var addClass = function addClass(element, className) {
		if (supportsClassList) {
			element.classList.add(className);
			return;
		}

		element.className += (element.className ? " " : "") + className;
	};

	var removeClass = function removeClass(element, className) {
		if (supportsClassList) {
			element.classList.remove(className);
			return;
		}

		element.className = element.className.replace(new RegExp("(^|\\s+)" + className + "(\\s+|$)"), " ").replace(/^\s+/, "").replace(/\s+$/, "");
	};

	var genericLoadEventName = "load";
	var mediaLoadEventName = "loadeddata";
	var errorEventName = "error";

	var addEventListener = function addEventListener(element, eventName, handler) {
		element.addEventListener(eventName, handler);
	};

	var removeEventListener = function removeEventListener(element, eventName, handler) {
		element.removeEventListener(eventName, handler);
	};

	var addEventListeners = function addEventListeners(element, loadHandler, errorHandler) {
		addEventListener(element, genericLoadEventName, loadHandler);
		addEventListener(element, mediaLoadEventName, loadHandler);
		addEventListener(element, errorEventName, errorHandler);
	};

	var removeEventListeners = function removeEventListeners(element, loadHandler, errorHandler) {
		removeEventListener(element, genericLoadEventName, loadHandler);
		removeEventListener(element, mediaLoadEventName, loadHandler);
		removeEventListener(element, errorEventName, errorHandler);
	};

	var eventHandler = function eventHandler(event, success, instance) {
		var settings = instance._settings;
		var className = success ? settings.class_loaded : settings.class_error;
		var callback = success ? settings.callback_loaded : settings.callback_error;
		var element = event.target;
		removeClass(element, settings.class_loading);
		addClass(element, className);
		callbackIfSet(callback, element);
		updateLoadingCount(instance, -1);
	};

	var addOneShotEventListeners = function addOneShotEventListeners(element, instance) {
		var loadHandler = function loadHandler(event) {
			eventHandler(event, true, instance);
			removeEventListeners(element, loadHandler, errorHandler);
		};

		var errorHandler = function errorHandler(event) {
			eventHandler(event, false, instance);
			removeEventListeners(element, loadHandler, errorHandler);
		};

		addEventListeners(element, loadHandler, errorHandler);
	};

	var managedTags = ["IMG", "IFRAME", "VIDEO"];

	var onEnter = function onEnter(element, instance) {
		var settings = instance._settings;
		callbackIfSet(settings.callback_enter, element);

		if (!settings.load_delay) {
			revealAndUnobserve(element, instance);
			return;
		}

		delayLoad(element, instance);
	};

	var revealAndUnobserve = function revealAndUnobserve(element, instance) {
		var observer = instance._observer;
		revealElement(element, instance);

		if (observer && instance._settings.auto_unobserve) {
			observer.unobserve(element);
		}
	};

	var onExit = function onExit(element, instance) {
		var settings = instance._settings;
		callbackIfSet(settings.callback_exit, element);

		if (!settings.load_delay) {
			return;
		}

		cancelDelayLoad(element);
	};

	var cancelDelayLoad = function cancelDelayLoad(element) {
		var timeoutId = getTimeoutData(element);

		if (!timeoutId) {
			return; // do nothing if timeout doesn't exist
		}

		clearTimeout(timeoutId);
		setTimeoutData(element, null);
	};

	var delayLoad = function delayLoad(element, instance) {
		var loadDelay = instance._settings.load_delay;
		var timeoutId = getTimeoutData(element);

		if (timeoutId) {
			return; // do nothing if timeout already set
		}

		timeoutId = setTimeout(function () {
			revealAndUnobserve(element, instance);
			cancelDelayLoad(element);
		}, loadDelay);
		setTimeoutData(element, timeoutId);
	};

	var revealElement = function revealElement(element, instance, force) {
		var settings = instance._settings;

		if (!force && getWasProcessedData(element)) {
			return; // element has already been processed and force wasn't true
		}

		if (managedTags.indexOf(element.tagName) > -1) {
			addOneShotEventListeners(element, instance);
			addClass(element, settings.class_loading);
		}

		setSources(element, instance);
		setWasProcessedData(element);
		callbackIfSet(settings.callback_reveal, element);
		callbackIfSet(settings.callback_set, element);
	};

	var isIntersecting = function isIntersecting(entry) {
		return entry.isIntersecting || entry.intersectionRatio > 0;
	};

	var getObserverSettings = function getObserverSettings(settings) {
		return {
			root: settings.container === document ? null : settings.container,
			rootMargin: settings.thresholds || settings.threshold + "px"
		};
	};

	var setObserver = function setObserver(instance) {
		if (!supportsIntersectionObserver) {
			return false;
		}

		instance._observer = new IntersectionObserver(function (entries) {
			entries.forEach(function (entry) {
				return isIntersecting(entry) ? onEnter(entry.target, instance) : onExit(entry.target, instance);
			});
		}, getObserverSettings(instance._settings));
		return true;
	};

	var nativeLazyTags = ["IMG", "IFRAME"];

	var shouldUseNative = function shouldUseNative(settings) {
		return settings.use_native && "loading" in HTMLImageElement.prototype;
	};

	var loadAllNative = function loadAllNative(instance) {
		instance._elements.forEach(function (element) {
			if (nativeLazyTags.indexOf(element.tagName) === -1) {
				return;
			}

			element.setAttribute("loading", "lazy");
			revealElement(element, instance);
		});
	};

	var nodeSetToArray = function nodeSetToArray(nodeSet) {
		return Array.prototype.slice.call(nodeSet);
	};

	var queryElements = function queryElements(settings) {
		return settings.container.querySelectorAll(settings.elements_selector);
	};

	var getElements = function getElements(elements, settings) {
		return purgeProcessedElements(nodeSetToArray(elements || queryElements(settings)));
	};

	var LazyLoad = function LazyLoad(customSettings, elements) {
		this._settings = getInstanceSettings(customSettings);
		this._loadingCount = 0;
		setObserver(this);
		this.update(elements);
	};

	LazyLoad.prototype = {
		update: function update(elements) {
			var _this = this;

			var settings = this._settings;
			this._elements = getElements(elements, settings);

			if (isBot || !this._observer) {
				this.loadAll();
				return;
			}

			if (shouldUseNative(settings)) {
				loadAllNative(this);
				this._elements = getElements(elements, settings);
			}

			this._elements.forEach(function (element) {
				_this._observer.observe(element);
			});
		},
		destroy: function destroy() {
			var _this2 = this;

			if (this._observer) {
				this._elements.forEach(function (element) {
					_this2._observer.unobserve(element);
				});

				this._observer = null;
			}

			this._elements = null;
			this._settings = null;
		},
		load: function load(element, force) {
			revealElement(element, this, force);
		},
		loadAll: function loadAll() {
			var _this3 = this;

			this._elements.forEach(function (element) {
				revealAndUnobserve(element, _this3);
			});
		}
	};
	/* Automatic instances creation if required (useful for async script loading) */

	if (runningOnBrowser) {
		autoInitialize(LazyLoad, window.lazyLoadOptions);
	}

	return LazyLoad;
});